Let's g the white house view, now, from abc's jake tapper, heading into that debate, as well. No question, a lot of pressure on mitt romney going into that debate. But the president also knows that challengers usually do well in that first debate. Reporter: That's right. The obama campaign says, if you look at the last six times that an incumbent faced a challenger, that the challenge earp in five out of six times was judged to be the winner of that first debate. So, they're trying to set expectations low. President obama has done a couple practice sessions at the democratic national headquarters with john kerry playing the role of mitt romney. And on sunday, he heads to a resort outside las vegas, where the president will have intensive debate preparations, george. One of the things they're working on, the president can sometimes get a little defensive when challenged. Reporter: That's right. And the first concern they have is the expectations game. But secondarily, there is this concern. President obama can show flashes of irritation. The you're likable enough hillary moment from the last campaign is one that resonates. They're trying to prevent that from happening, george. Jake tapper, thanks very much. Next wednesday night.

This transcript has been automatically generated and may not be 100% accurate.

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